The former NFL running back was found dead in a California prison, a spokeswoman for the California Department of Corrections and Rehabilitation confirmed to USA TODAY.

The death is being investigated as a suicide. Phillips was 40.

The former University of Nebraska star was facing the possibility of the death penalty for allegedly murdering his former cellmate at Kern Valley State Prison, the same prison he was found dead. Phillips was sentenced to a lengthy sentence after being convicted of choking his girlfriend and also driving his car into a pickup football game.

Phillips was taken No. 6 overall in the first round of the 1996 NFL Draft by the St. Louis Rams. He played 15 games in his rookie season, totaling just 632 yards on 193 carries. He had a decent season in 1997 with the Rams and then the Dolphins, rushing for 677 yards and eight touchdowns in just 12 games. He was released by the Dolphins in 1998 after pleading no contest to assaulting a woman at a Florida nightclub.

Phillips eventually returned to the NFL in 1999, which ended up being his final season in the NFL. His work ethic came into question and issues with the coaching staff led to his release during the 1999 season.